Scientific name: Inonotus obliquus (Ach. ex Pers.) Pilat.
Derivation of name: Obliquus means "slanted" or
Synonyms: Boletus obliquus Ach. ex Pers., Polyporus
obliquus (Ach. ex Pers.) Fr.; Poria obliqua (Ach. ex Pers.)
Common name(s): Clinker polypore, birch conk,
canker polypore, chaga.
Occurrence on wood substrate: Parasitic; sterile conk
made of compacted hyphae forming almost exclusively
of living birch (Betula) species; conks found
Dimensions: The sterile, black clinker- or cinder-like knobs
or conks can be quite large, 10-40 cm across and irregular in
Description: Resembling charred wood or a canker-like
growth, the outer surface of the sterile conk is dark brown
black, hard, and deeply fissured. Internally, the tissue is
and yellow to yellow-brown.
Edibility: Used to make a tea called chaga.
Comments: In addition to the sterile conk, the species
an effused, poroid fruiting body beneath the bark or
layers of wood on snags or fallen trunks. This fertile
is not commonly found and will not be
described. Chaga tea is prepared from the sterile
More information at Rogersmushrooms.com
Figure 1. Inonotus obliquus on paper birch (Betula
Photo © Greg Marley.
Inonotus obliquus on yellow birch (Betula
alleghaniensis). Photo © Gary Emberger.
Figure 3. A rather elongate specimen. Photo © John
Figure 4. Rick Van de Poll refers to conks shaped like
this as "pig snout specials." Photo © Rick Van de Poll.
5. The dark, cracked outer surface of the sterile
Photo © Gary Emberger.
Internally, the clinker polypore is yellowish to
yellow-brown. Photo© Gary Emberger.
Figure 7. Section throrugh
Inonotus obliquus showing
attachment to the wood. Detaching the clinker polypore
often requires a hatchet or hammer.
Photo © John Plischke III.
Tea preparation involves breaking chaga into small
pieces. Photo © John Plischke III.
A coffee grinder can be used to prepare a fine
powder used to make chaga tea. Photo © John Plischke III.